This invention relates, in general, to fabrication of field emission devices, and more particularly, to fabrication of field emission devices employing semiconductor material.
Field emission devices (FEDs) are known in the art. Commonly, FEDs include an electron emitter that has at least one geometric discontinuity of a small radius of curvature such as a sharp tip or sharp edge and an extraction electrode that is proximally disposed with respect to the electron emitter so that upon application of a suitable potential between the extraction electrode and the electron emitter electrons are emitted into a free-space region.
Several, methods for realizing physical embodiments of FEDs are also known. A first method employs directional evaporation of conductive materials into a cavity to form an electron emitting cone. A second method employs a wet selective anisotropic etch that etches a crystalline material to provide an electron emitter having a desired geometric discontinuity of small radius of curvature. A third method employs anisotropic etching to provide features that are employed as molds into which material is deposited to subsequently function as an electron emitter.
In the prior art, corresponding to the first method, fabrication complexities associated with the material evaporation impose manufacturing constraints.
The second method previously mentioned suffers from performance limitations associated with known fabrication techniques.
The third method previously mentioned suffers from fabrication complexity, difficulties in manufacture, and lack of ruggedness.
In addition, the prior art methods that employ crystalline material substrates having an electron emitter formed therefrom typically are not capable of having an adequate insulating layer height to a cavity aperture diameter ratio of greater than approximately 0.75.
Accordingly, there exists a need for a method of forming field emission devices which overcome at least some of the shortcomings of the prior art.